OF THE MAMMALIAN OSSICULA AUDITUS. 451 



The malleus of B. mysticetus (PI. LXII. fig. 28) measures about half an inch or a little 

 more in length. The head is very large ; its intero-inferior aspect is smooth and quite 

 convex ; externally and a little anteriorly it is very deeply excavated, the upper border 

 of the cavity extensively overhanging it, especially towards the front, whilst behind there 

 is a deep notch in that border. Hyrtl justly compares the excavation to that seen in the 

 anterior aspect of the malleus of the Seal (Bhoca) ; and from the extremely overhanging 

 border, the bone assumes a form seen in certain shells, as Van Beneden has observed ; 

 indeed, putting aside the articular region and manubrium, the head much resembles the 

 tympanic bone to wbich it is attached. On its upper aspect is situated the articular 

 surface, which looks a little inwards and is deeply concave. It is made up of two 

 facets, both of a semicircular form ; the upper and external is almost plane, and by far 

 the most extensive ; it is separated from the lower, which is convex, by a sharp groove. 

 In front of the head, on the outer aspect, is a deep channel, distinct superiorly, but 

 absent below. This cuts off a portion of the malleus, which, close to the channel, is 

 broad and flattened, bearing a distinct tubercle (PL LXII. fig. 28, & PL LXIII. fig. 13, 

 pm), which projects upwards and inwards ; but beyond the tubercle it gradually nar- 

 rows as it runs forwards, ending in a hook-like point (mn), which curves downwards and 

 outwards, and is longer and narrower in B. australis than in B. mysticetus. The 

 tubercle (pm) is the processus muscularis, as may be seen in preparation No. 1598 B in 

 the Physiol. Ser. Coll. Surg., where the tensor tympani muscle remains still attached to 

 it. The hook-like process (mn) is without doubt the true manubrium ; into it is inserted 

 the apex of the curious prolongation of the membrana tympani characteristic in this 

 Order. 



The homologous parts of the malleus in Balcena (PL LXIII. fig. 13) may be com- 

 pared with the same in the more familiar malleus of Felis (PL LXIII. fig. 14). 



Cuvier states, in his ' Lecons d' Anatomie Comparee,' that in the Dolphin there is no 

 manubrium, and that the malleus of the Whale " resembles it in every respect, but is 

 double its size." Hyrtl (I. c.) correctly denies this assertion, and remarks of the Ceta- 

 cean manubrium : — " It is only very short, and reduced to a rounded bony tubercle,, 

 separated by a deep incision from the head. . . . The processus minor [sic] is represented 

 by two small pointed appendages, to which a triangular process of the membrana tym- 

 pani attaches itself." But Van Beneden remarks* of Balcena mysticetus: — "The 

 malleus possesses neither any distinct apophyses nor a manubrium." Lastly, Huxley f 

 asserts, in describing the anatomy of the Porpoise : — " The tympanic membrane is 

 concave externally; and, as is usual in the Cetacba, is connected by a ligament 

 with the handle of the malleus." I cannot see how the curved process of the malleus 

 of Balcena can represent any thing otherwise than the inflected splinter of bone on the 

 blunt extremity of the malleus of the Dolphin $, which is the true manubrium of all other 

 mammals ; and, judging both by analogy and by the preparation above referred to, the 



* ' Osteographie des Cetaces,' Van Beneden and Gervais. 

 t ' Manual of the Anatomy of Vertebrated Animals,' 1871. 

 t PI. LXIII. fig. 15, mn, from a Globioeephalus. 



